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Date: Tue, 23 Apr 2019 09:36:22 -0400
From: Tony Krowiak <akrowiak@...ux.ibm.com>
To: pmorel@...ux.ibm.com, linux-s390@...r.kernel.org,
linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc: freude@...ux.ibm.com, borntraeger@...ibm.com, cohuck@...hat.com,
frankja@...ux.ibm.com, david@...hat.com, schwidefsky@...ibm.com,
heiko.carstens@...ibm.com, pasic@...ux.ibm.com,
alex.williamson@...hat.com, kwankhede@...dia.com
Subject: Re: [PATCH v2 7/8] s390: vfio-ap: handle bind and unbind of AP queue
device
On 4/23/19 9:08 AM, Pierre Morel wrote:
> On 20/04/2019 23:49, Tony Krowiak wrote:
>> There is an implied guarantee that when an AP queue device is bound to a
>> device driver, that driver will have exclusive control over the device.
>> When an AP queue device is unbound from the vfio_ap driver while the
>> queue is in use by a guest and subsquently bound to a zcrypt driver, the
>> guarantee that the zcrypt driver has exclusive control of the queue
>> device will be violated. Likewise, when an AP queue device is bound to
>> the vfio_ap device driver and its APQN is assigned to an mdev device in
>> use by a guest, the expectation is that the guest will have access to
>> the queue.
>>
>> The purpose of this patch is to ensure three things:
>>
>> 1. When an AP queue device in use by a guest is unbound, the guest shall
>> no longer access the queue. Due to the limitations of the
>> architecture, access to a single queue can not be denied to a guest,
>> so access to the AP card to which the queue is connected will be
>> denied to the guest.
>>
>> 2. When an AP queue device with an APQN assigned to an mdev device is
>> bound to the vfio_ap driver while the mdev device is in use by a
>> guest,
>> the guest shall be granted access to the queue.
>>
>> 3. When a guest is started, each APQN assigned to the guest's mdev device
>> must be owned by the vfio_ap driver.
>>
>> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
>> ---
>> drivers/s390/crypto/vfio_ap_drv.c | 16 ++++++-
>> drivers/s390/crypto/vfio_ap_ops.c | 82
>> ++++++++++++++++++++++++++++++++++-
>> drivers/s390/crypto/vfio_ap_private.h | 2 +
>> 3 files changed, 97 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/s390/crypto/vfio_ap_drv.c
>> b/drivers/s390/crypto/vfio_ap_drv.c
>> index e9824c35c34f..0f5dafddf5b1 100644
>> --- a/drivers/s390/crypto/vfio_ap_drv.c
>> +++ b/drivers/s390/crypto/vfio_ap_drv.c
>> @@ -42,12 +42,26 @@ MODULE_DEVICE_TABLE(vfio_ap, ap_queue_ids);
>> static int vfio_ap_queue_dev_probe(struct ap_device *apdev)
>> {
>> + struct ap_queue *apq = to_ap_queue(&apdev->device);
>> + unsigned long apid = AP_QID_CARD(apq->qid);
>> + unsigned long apqi = AP_QID_QUEUE(apq->qid);
>> +
>> + mutex_lock(&matrix_dev->lock);
>> + vfio_ap_mdev_probe_queue(apid, apqi);
>> + mutex_unlock(&matrix_dev->lock);
>> +
>> return 0;
>> }
>> static void vfio_ap_queue_dev_remove(struct ap_device *apdev)
>> {
>> - /* Nothing to do yet */
>> + struct ap_queue *apq = to_ap_queue(&apdev->device);
>> + unsigned long apid = AP_QID_CARD(apq->qid);
>> + unsigned long apqi = AP_QID_QUEUE(apq->qid);
>> +
>> + mutex_lock(&matrix_dev->lock);
>> + vfio_ap_mdev_remove_queue(apid, apqi);
>> + mutex_unlock(&matrix_dev->lock);
>> }
>> static void vfio_ap_matrix_dev_release(struct device *dev)
>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c
>> b/drivers/s390/crypto/vfio_ap_ops.c
>> index 31ce30ee784d..3f9506516545 100644
>> --- a/drivers/s390/crypto/vfio_ap_ops.c
>> +++ b/drivers/s390/crypto/vfio_ap_ops.c
>> @@ -763,8 +763,8 @@ static void vfio_ap_mdev_wait_for_qempty(unsigned
>> long apid, unsigned long apqi)
>> msleep(20);
>> break;
>> default:
>> - pr_warn("%s: tapq err %02x: 0x%04x may not be empty\n",
>> - __func__, status.response_code, q->apqn);
>> + pr_warn("%s: tapq err %02x: %02lx%04lx may not be empty\n",
>> + __func__, status.response_code, apid, apqi);
>> return;
>> }
>> } while (--retry);
>> @@ -823,6 +823,14 @@ static int vfio_ap_mdev_reset_queues(struct
>> mdev_device *mdev)
>> static int vfio_ap_mdev_create_shadow_crycb(struct ap_matrix_mdev
>> *matrix_mdev)
>> {
>> + /*
>> + * If an AP resource is not owned by the vfio_ap driver - e.g.,
>> it was
>> + * unbound from the driver while still assigned to the mdev device
>> + */
>> + if (ap_apqn_in_matrix_owned_by_def_drv(matrix_mdev->matrix.apm,
>> + matrix_mdev->matrix.aqm))
>> + return -EADDRNOTAVAIL;
>> +
>> matrix_mdev->shadow_crycb =
>> kzalloc(sizeof(*matrix_mdev->shadow_crycb),
>> GFP_KERNEL);
>> if (!matrix_mdev->shadow_crycb)
>> @@ -847,6 +855,18 @@ static int vfio_ap_mdev_open(struct mdev_device
>> *mdev)
>> if (!try_module_get(THIS_MODULE))
>> return -ENODEV;
>> + ret = ap_apqn_in_matrix_owned_by_def_drv(matrix_mdev->matrix.apm,
>> + matrix_mdev->matrix.aqm);
>> +
>> + /*
>> + * If any APQN is owned by a default driver, it can not be used
>> by the
>> + * guest. This can happen if a queue is unbound from the vfio_ap
>> + * driver but not unassigned from the mdev device.
>> + */
>> + ret = (ret == 1) ? -EADDRNOTAVAIL : ret;
>> + if (ret)
>> + return ret;
>> +
>> matrix_mdev->group_notifier.notifier_call =
>> vfio_ap_mdev_group_notifier;
>> events = VFIO_GROUP_NOTIFY_SET_KVM;
>> @@ -938,3 +958,61 @@ void vfio_ap_mdev_unregister(void)
>> {
>> mdev_unregister_device(&matrix_dev->device);
>> }
>> +
>> +static struct ap_matrix_mdev *vfio_ap_mdev_find_matrix_mdev(unsigned
>> long apid,
>> + unsigned long apqi)
>> +{
>> + struct ap_matrix_mdev *matrix_mdev;
>> +
>> + list_for_each_entry(matrix_mdev, &matrix_dev->mdev_list, node) {
>> + if (test_bit_inv(apid, matrix_mdev->matrix.apm) &&
>> + test_bit_inv(apqi, matrix_mdev->matrix.aqm))
>> + return matrix_mdev;
>> + }
>> +
>> + return NULL;
>> +}
>> +
>> +void vfio_ap_mdev_remove_queue(unsigned long apid, unsigned long apqi)
>> +{
>> + struct ap_matrix_mdev *matrix_mdev;
>> +
>> + matrix_mdev = vfio_ap_mdev_find_matrix_mdev(apid, apqi);
>> +
>> + /*
>> + * If the queue is assigned to the mdev device and the mdev device
>> + * is in use by a guest
>> + */
>> + if (matrix_mdev && matrix_mdev->kvm) {
>> + /*
>> + * Unplug the adapter from the guest but don't unassign it
>> + * from the mdev device
>> + */
>> + clear_bit_inv(apid, matrix_mdev->shadow_crycb->apm);
>> + vfio_ap_mdev_update_crycb(matrix_mdev);
>> + }
>> +
>> + vfio_ap_mdev_reset_queue(apid, apqi);
>> +}
>> +
>> +void vfio_ap_mdev_probe_queue(unsigned long apid, unsigned long apqi)
>> +{
>> + struct ap_matrix_mdev *matrix_mdev;
>> +
>> + matrix_mdev = vfio_ap_mdev_find_matrix_mdev(apid, apqi);
>> +
>> + /*
>> + * If the queue is assigned to the mdev device and the mdev device
>> + * is in use by a guest
>> + */
>> + if (matrix_mdev && matrix_mdev->kvm) {
>> + /* Plug the adapter into the guest */
>> + set_bit_inv(apid, matrix_mdev->shadow_crycb->apm);
>> +
>> + /* Make sure the queue is also plugged in to the guest */
>> + if (!test_bit_inv(apqi, matrix_mdev->shadow_crycb->aqm))
>> + set_bit_inv(apqi, matrix_mdev->shadow_crycb->aqm);
>
> Why are you testing the domain before setting it and not the adapter?
>
> Eventually you do not need to test at all or if, then both.
My thinking was that when a queue is removed, we clear only the APID
from the APM, but do not clear the APQI from the AQM. I think you are
correct in saying we do not need to test either mask since we are
plugging the queue in regardless.
>
> NIT
>
>
>> +
>> + vfio_ap_mdev_update_crycb(matrix_mdev);
>> + }
>> +}
>> diff --git a/drivers/s390/crypto/vfio_ap_private.h
>> b/drivers/s390/crypto/vfio_ap_private.h
>> index e8457aa61976..00eaae3b853f 100644
>> --- a/drivers/s390/crypto/vfio_ap_private.h
>> +++ b/drivers/s390/crypto/vfio_ap_private.h
>> @@ -87,5 +87,7 @@ struct ap_matrix_mdev {
>> extern int vfio_ap_mdev_register(void);
>> extern void vfio_ap_mdev_unregister(void);
>> +void vfio_ap_mdev_remove_queue(unsigned long apid, unsigned long apqi);
>> +void vfio_ap_mdev_probe_queue(unsigned long apid, unsigned long apqi);
>> #endif /* _VFIO_AP_PRIVATE_H_ */
>>
>
>
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